Conventional down fabric constructions often include nonwoven filler material enclosed between two woven fabric “shell” layers. These nonwoven filler materials are known to provide a relatively high level of thermal insulation, and are lightweight with very good packability.
Some known nonwoven filler materials, such as Primaloft®, available from Albany International Corp, and Thinsulate™, available from 3M Company, are prone to movement and fibers of the nonwoven filler material often have a tendency to protrude through the woven fabric layers. To inhibit this fiber migration, it is known to quilt the filler material to one or both of the woven fabric layers. The quilting, however, tends to flatten the nonwoven filler material, and, as a result, can reduce the thermal insulation of the fabric construction. The quilting may also inhibit the fabric construction from stretching.
To inhibit migrating fibers from protruding through the woven fabric layers, the woven fabric layers are often made of a very tight construction with an air permeability of less than 1.0 ft3/ft2/min and, in many cases, close to zero ft3/ft2/min. In some cases, the woven fabric is calendared, being passed through heated rolls under high pressure, to seal voids in the tight woven construction. In certain circumstances, a chemical system is applied to the woven fabric prior to calendaring to help seal voids in the woven fabric. This type of sealing may reduce the air permeability of the fabric construction to almost zero ft3/ft2/min. As a result, a garment made from the resulting fabric constructions may have reasonable insulation, but poor air permeability and, as a result, low breathability.
Nonwoven filler materials also tend to flatten under compression and as a result may exhibit a loss in thermal insulation.